Outside the window, on the other side of the tidy hedge, lay a small London street where darkness had fallen. Across it, under the streetlight, two women walked by and their animated chat was quite audible through the window. Laurence thought the room seemed too ordinary to contain the man in front of him.

'Yes,' said Somers, finally. Then he repeated himself, 'Yes. Wasn't that enough?'

Wasn't that enough? Leonard Byers had said that the last time Laurence had seen him. It was an epitaph for the whole grim mess. He waited for the other man to collect himself.

'Tucker died too easily,' Somers went on. 'Corporal Byers, too: a man more used to making beds and heating an officer's canteen than putting his life on the line. Your friend Captain Emmett said Byers was fussing about his wet feet while they were waiting to shoot my son and then he walked up to my boy, a condemned man within seconds of death, and tore off his badges. It was simply an act to humiliate him. Gratuitous.'

He was white-faced.

'As for Inspector-late Assistant Provost Marshal-Mullins, he was a cold, hard man who believed the worst of everybody. From my committee work I know that more men, whether guilty or simply unfortunate, were ensured of capture, arrest or execution under Mullins' aegis than any other. Although I took enormous risks in shooting him in broad daylight, so close to Scotland Yard, it was worth it. I was never worried for myself but simply that I would be prevented from finishing off my work.'

Laurence could hear his own breath. It sounded uneven and he hoped it wasn't audible to Somers. The last time he remembered feeling like this was in France. He shifted slightly to ease the pressure on his spine. Somers' revelations were exactly what he had feared, yet could never possibly have expected from a man of his standing.

'You wanted to remove everyone involved in your son's death?'

'Of course not.' Somers looked surprised. 'I accept military necessity. I only ever wanted the guilty to be punished. There were six officers of the court martial. Despite sentencing my son to death, they recommended mercy on account of his age. For this, I spared the four who had survived the war: Ryecraft, Vane-Percy, Goose and O'Shea.'

Somers recited their names effortlessly, ticking them off on his fingers. How many times had he gone through the case papers, Laurence wondered? He doubted whether even Brabourne would have known the name of every member of the board.

'Harry's CO-a chap called Gooden, whose evidence damned Harry-died in an accident on the grouse moor on the opening day of the season in 1919.'

Somers smiled, without showing his teeth.

'Shot by a keeper. Presumably in error. My only targets were Emmett, Tucker, Byers, Mullins, Lilley and General Hubert Gough. All, bar Gough, are now dead. The Honourable Ralph Lilley-the subaltern who had been so eager to condemn Harry, simply from spite and dislike-lived conveniently close to my home. We knew the family slightly, though of course he had no idea of my link to Harry. I followed him for a while, observing his habits. Watched my quarry settle back into the comfortable life he'd led before the war. Lilley took a regular train from our local station. It was the most natural thing in the world to join him, talk to him on the platform and then push him under the incoming train. These things are never quite straightforward: he fell too far out and the train merely cut off his legs rather than killing him outright. But I jumped down on to the tracks and was able to tell him why he was dying, before help came and he bled to death. I was the unknown hero of the hour.'

Laurence found it hard to process what he was hearing. How long had he been here, listening to a man who should have been the sanest of individuals, and whose demeanour and tone were indeed utterly reasonable, talking of madness?

'I can see your skills deserted you there,' said Somers. 'Perhaps you didn't get as far as Lilley. You didn't use your imagination.'

'Do you know, I've had enough of people telling me what I should have done,' said Laurence, fatigue and discomfort crushing the instinct to placate the man in front of him. 'I now know why John Emmett died, even if I don't know exactly how. I set out to unravel that and that alone. John's path crossed, disastrously, with your son's and with you, but all I ever wanted was an answer for his sister. I have that answer. And for her it may now be much simpler to come to terms with her brother's death. Knowing his life was taken by you, not thrown away by him,' he said, recalling both Byers' and Eleanor's comments about the relative pain of the suicide or the murder of a loved one.

Somers' face contorted slightly. He looked puzzled. 'You think someone killing someone you love is easier to bear than knowing they took their own life?' For the first time, he fell silent.

'Yes. However you might have chosen to punish the men you condemned, for John Emmett's sister, at least, I think the truth will be terrible but less hard than it was.' And then, still angry, he added, 'I did know about Lilley and you got the wrong man in Byers. He wasn't the man on the execution detail.'

'There you are wrong. Emmett identified Byers on the photograph. Described him. Told me precisely how he'd fussed about his wet feet-had degraded my son in his last minutes. I tracked him down to the very farm he'd enlisted from.'

Although Somers spoke firmly, a faint doubt showed in his face.

'That was his cousin,' said Laurence. 'There's a family resemblance, I'm told, but he was a cousin. You killed Jim Byers. Jim Byers just did his bit in France for three years. Leonard Byers is alive and well.'

He was angry because Somers was wrong. In this war every man's life had been on the line. Batmen and bandsmen had fixed their bayonets alongside their comrades. There was no escape.

Somers looked disconcerted only for a second and then, unexpectedly, he laughed, a laugh that filled the room with something like normality.

'Of course he's well,' he said, with just a trace of bitterness. 'Mr Leonard Byers, successful civilian. Of course he is. I told you he was a man with an eye for the main chance. Warm feet now, no doubt. Still, I'm sorry about the cousin if it's true. Dismal, run-down place the farm was, too. Not much sign of Mr Lloyd George's land fit for heroes down there. Scarcely fit for cows. But I am sorry. Not that any of it matters now.'

'And you were seen,' Laurence said, realising that for all his reasonable manner, part of Somers was irreparably and unpredictably damaged. 'Byers' old uncle, semi-bedridden, was at a window when you arrived with your gun. He was a weak witness, shocked and bemused, but he was still a witness.' His words came out more strongly than he'd intended.

'I was seen, as you put it, before I pushed Lilley under the train. I was seen by plenty of people when I shot Mullins. There's seeing and not seeing. Age, expectation and authority: they're all surprisingly effective disguises, Mr Bartram, especially to certain witnesses.'

Laurence looked at the window. It was now completely dark outside. Where was Gwen Lovell?

'I wasn't merciless, you know. I checked them all. The other men connected with my son's death are more or less blameless or dead. One-Private Watkins-endures a living death in the North Wales County Lunatic Asylum.

'Since the death of Mullins, things have become harder but my hand was forced before I was ready when I realised Mullins might be piecing things together. It was Gough I wanted, above all. Gough served with me in Africa. I knew him. He deserved to die. An ambitious man. An incompetent commander. Callous, arrogant; I doubt he even bothered to read through Harry's defence.

'In those crucial days when the top brass were weighing Harry's fate in their hands, even General Shute, who had no respect for Harry's division and whom the men hated, pointed out that Harry was very young. So I let Shute live. The request for confirmation of sentence rose upwards until it reached Gough. Gough rejected a unanimous call for clemency by the officers of the court martial. Gough said with zeal that he "recommended" that sentence be carried out. Only rank distinguished him and Tucker: brutal men who revelled in war's cruelty and humiliations. He's been in Switzerland. But now he's back. And I have waited for him.'

There was absolute silence. Laurence had heard a single car pass by and a door slam across the road; the sounds provided a comfortable, though brief, assurance that there were people out there. Was Gwen Lovell listening to all this? Had she known all along what Somers was planning or what he'd done? While he was certain she hadn't known when he had first come to her house, he sensed that she did now. She had aged twenty years since then.

'Mullins came to see me after Emmett vanished. Very polite, of course. A favourite nephew had been a patient at Holmwood, as bad luck would have it. The late Inspector Mullins was obviously a very well-connected man. The boy had no father so Mullins was up and down to see him. He made a miraculous recovery. So Dr Chilvers, not putting vast store by the local constabulary, had asked Mullins to cast an eye over Emmett's disappearance as a personal favour. Bad for the place's carefully built reputation to lose a patient. It was Chilvers who told Mullins that Emmett had been in touch with members of the Darling Committee and was obsessed with the Hart execution. All the same, it should have been a formality for a busy senior police officer from another force. Eventually I had to concede to Mullins I'd visited Emmett at Holmwood. Chilvers was bound to tell him. I said Emmett had been a friend of Hugh.'

The army friend that the staff at Holmwood had described, Laurence thought. He had simply assumed it was a wartime contemporary of John's. How careless he'd been.

'Mullins was sharp. He seemed to be satisfied but he obviously kept turning it over. He remembered Hart's execution, of course. Then Emmett was found dead and Mullins thought a little harder.'

'And Mullins was briefly involved in investigating Jim Byers' death,' Laurence said.

'I didn't know that,' Somers said, obviously digesting this new information. 'Perhaps he was already looking out for connections? A clever man. But Dr Chilvers knew of Emmett's assault on Tucker-it was why he had been admitted: to escape prosecution for assaulting a policeman in that fracas-and that, too, Chilvers passed on to Mullins. Tucker was also dead, as Mullins discovered from the Birmingham force. Too many coincidences. At some point he commandeered Harry's file and tracked down the letter I'd written, pushing for him to be given a commission. He came to talk to me. I don't know if he ever knew about Lilley. His death was carried in The Times, so it was likely. Lilley lived and died just two miles from my house. Sooner or later Mullins would have approached Gwen because of Emmett's wretched bequest. Then, a week before his death, he asked me to come and see him again when I was next in London. Nothing urgent, so he said.

'I couldn't risk it any more but, anyway, he'd always been on my list. The perfect public servant. Duty and inflexibility. I went up to London, and the rest you know. The police were always going to go flat out once nemesis had caught up with Mullins. He'll have kept a record. Today it's you on the doorstep, tomorrow it will be them.'

Somers got up and came towards him. Laurence tensed himself, but Somers simply walked unevenly past him to the window. Charles had said he had been wounded in South Africa. Somers stood looking out at the darkness, with his back to Laurence. Laurence wondered whether he should make a run for it. With his back so stiff, he doubted he'd get far. Who would win if it came to a tussle, and what part might Gwen Lovell play?

'Brabourne was so clear about what happened at the trial but I smelled a rat when he became vague about the execution itself,' said Somers, still gazing out. 'I didn't want to alert him with too many questions, and I had to keep my emotions tightly under control. Eventually he revealed that Harry hadn't died immediately. It had a taken a coup de grace. Which meant Emmett should have put the last bullet in his brain. Except that Brabourne's essential decency covered up Emmett's disgrace. It took Emmett himself to tell me what had really happened.'

Laurence was finding it increasingly hard to concentrate. He knew how the story Somers was now telling would end. He wished he hadn't sent Charles away.

'Emmett and I talked for an hour or so at the Coburg in the first instance,' Somers continued, 'just establishing the outline of it all. I couldn't push him too hard as I didn't want him to be uneasy, and he needed to get back to Holmwood before the police were called to find him. I put him on a train. Made arrangements to meet again. I wanted to get him to my own house, away from onlookers, with time to go through it all. I wanted to make sure I got every fact, every name. To know exactly what happened and who was involved.'

He glanced at Laurence more directly.

'But Emmett knew it would be very difficult to escape from Holmwood a second time.'

He paused.

'And I knew that once I'd persuaded him to come to see me, he would have to disappear, you see. He was a link to me and I had my mission to complete. I didn't care about surviving myself but I did care about justice.'

Somers was almost persuasive, his tone of voice reasonable.

'I told Gwen to write to him. To ask to meet him. To suggest myself, as he had already met me, as an intermediary. To say that I lived not far from Holmwood, that I could arrange it. She wrote in good faith, believing it would happen-and Emmett had absolutely no idea that I knew Gwen other than professionally. But, as I said, he was desperate to see her. She was the lure. However, I had absolutely no idea that he had left Gwen a bequest, which meant that his death would lead straight back to her.

'I set up the final meeting at my house in Oxfordshire. When he arrived, Gwen was not there, needless to say, but Emmett didn't really seem surprised. He just wanted to talk. He told me every damn thing about Harry. His poetry. His trial. His death. Harry's persecutors and those few who tried to help him. Above all, Emmett gave me the names and each individual's portion of guilt became clear. I promised to tell Harry's mother everything.'

He stopped again, and then he said in a slower voice, 'I have thought about it since, of course. Did I feel pity for Emmett? Obviously he had suffered. Nerves, mostly. His right arm was useless, you know? When I had seen him for the first time, I assumed he'd been wounded but it wasn't that. Nothing really wrong with the arm at all, but plenty wrong in the mind.

'But, do you know, during the long hours he was with me, I thought there had been some sort of lightening of his spirit, as if by telling me everything he had rid himself of his guilt. In the end I told him the truth. He had been so honest. He had emptied himself out. So I told him Harry was my son. I wanted to tell somebody at last.'

'What did he say?'

'He asked me to forgive him.'

Laurence felt numb. It was so simple.

'I told him there was nothing to forgive,' said Somers. 'It was war.'

'But you didn't forgive the others?'

'The others didn't ask.' He paused.

'Emmett told me that at the last minute he realised that he knew my son. He'd actually met him once. They shared a deep love of poetry. Harry's last words were supposed to have been, "For God's sake shoot quickly and get it over with," but when he fell to the ground he was only injured. Refused a blindfold.'

Pain was unmistakable on Somers' face. His speech slowed.

'He had blue eyes, like his mother.'

He wiped his forehead, hesitated.

'Emmett just stood there. Frozen, he said. Harry tried to speak. Emmett had his gun in his hand; everybody waiting for him to do his duty. He said Harry was unintelligible. Then Sergeant Tucker, who hadn't marched the men away but left them gawping, quit the line, came forward, cool as you like, took the gun from Emmett, who put up no kind of resistance, and he shot Harry straight in the face.

Chapter Thirty-seven.

The two men looked at each other. Both started to speak at once, then stopped. It was as if all the chaos of murder, adultery, suicide and illegitimacy had been reduced to mere social awkwardness.

Finally Laurence said, And now? What do you intend to do?'

'I imagine if you leave here you'll go straight to fetch the police?' Somers looked up. At last Laurence could hear Gwen Lovell move at the back of the house.

'I just didn't really think...' Laurence began. Did Somers intend to let him go and if not, what would he do?

'Oh, you think,' said Somers. 'You're a brave man. Brave and dogged. An excellent officer. Acting major. Twice mentioned in despatches and holder of the Military Cross. How does the citation go? "For conspicuous courage under fire. Leading an attack against considerable odds, in which the battalion sustained heavy losses, he returned to retrieve the injured at considerable risk to himself." You think, Captain Bartram. You think very carefully and you act decisively. If you didn't count on my finding you, you certainly knew it was a possibility you would find me.'

He was trying to heave the dead weight of Pollock, pitiable, fat Pollock, back across the churned-up terrain. Bent half double, he strained to drag him by the legs. Pollock's weight made a trough in the mud and as Laurence leaned forward he could smell the urine soaking through the soldier's trousers. He hoped the man was unconscious-the body kept lurching to the side and every time he managed to move him more than a few inches, Pollock made a wet, wheezing sound and red froth came out of his mouth. The front of his tunic was black and tarry. Laurence hadn't dared open it in case it was all that was keeping Pollock's guts inside his body. Suddenly the ground fell away and they were both tumbling into a crater of mud and water. The tremendous weight of the injured man landed on top of him. For a minute he lay winded and nauseated, then panicked and struggled furiously to get a purchase on Pollock's jacket. At last he tore himself free but his legs had lost all feeling. He sat in the slime holding the man's head in his lap. There was faint sunlight now, piercing the smoke, as the water around the soldier turned reddish brown and strings of pink saliva congealed between his bloody teeth. He sat and stroked Pollock's cold face until someone came and found them.

Somers was still talking.

'Did you really believe you were the only one capable of a bit of detective work? It's not hard to find a man's records, you know. To talk to a few people.'

He was getting up as he spoke. He returned to the bureau and opened a different drawer. Laurence wondered what he was about to show him. Somers rifled through some papers and turned round. He was holding a gun.

'Believe it or not, I regret the need for this,' Somers said. 'But, you see, Brabourne contacted me a day or so ago asking what had happened to the photograph he'd given me. Emmett stole it from my house, of course, after I showed it to him. I never even noticed its absence. I gather it came home with his effects? I had to improvise, say there'd been a burglary. But it wouldn't do. I knew you'd come back to Gwen sooner or later and now the journalist was suspicious too. He asked me if I had known Mullins. If I knew that Emmett was dead.'

He sat down, still holding the gun. It was hardly different from the Webley that Laurence had used in the war.

'Did John take anything else?' Laurence thought Somers hesitated but realised the man was simply tiring. Somers shook his head and carried on talking.

'Gough. He was the ultimate arbiter. He had my son's life in his hands. I simply want him now. After that, I don't care. What difference does it make to me? I'll hang, Gwen will be disgraced either way. If I shoot you now, I might get Gough and we might just get away. I have tickets for Gwen, Catherine and myself to sail to Canada in January. I chose the anniversary of Harry's death. By then it all needs to be finished.'

He looked at Laurence almost questioningly as if asking for his approval.

'I can't let you stop me before I've dealt with Gough.'

'I think there would be a difference to you in killing me,' Laurence said steadily.

The Webley looked well maintained. Was it loaded? Somers was not yet pointing it at him, but held it by his side. Laurence was surprised to find just how much he wanted to live. He wondered what Mary would feel if he died.

'As you say, it all depends on motive,' he continued, amazed that his voice was steady. 'In war there's little choice. We both know that. Killing is abhorrent to start with, but it becomes routine. Possibly you felt you had no choice with the men involved in Harry's death, which makes it a noble cause in your eyes. But shooting me would be for nothing more than your own convenience. You might justify it on the grounds of protecting Mrs Lovell, but I don't think that's what she'd want, certainly not here in her own house and probably not anywhere, for that matter. I don't think you want to shoot me. I suspect you're weary of the whole thing.'

He hoped it was true.

'You could be right,' Somers said slowly. 'I lied even to her. Denied I'd ever seen Emmett. It can't be done here.'

He stopped speaking and seemed to be finding it hard to concentrate, though the gun was now pointing directly at Laurence, who was now sure it was loaded.

'It's a bad business about Byers. But it doesn't take away the justice of my mission. If you'd had a son, you'd understand.'

Actually, I did have a son,' said Laurence. 'He died too.'

In the end it was such a simple thing to say.

Somers seemed distracted by his response. The gun dropped again.

'I'm sorry. This is a bad business.'

He rubbed his eyes. Any energy in him was suddenly gone. He deflated almost visibly.

'Do you know, I feel terribly old all of a sudden? I thought I'd fought my wars long ago. I'll be glad when all this is finished...'

Then he seemed to recollect himself and looked straight at Laurence.

'Because you were so close, I finally had to tell her,' he said bitterly. 'Telling Gwen the truth, was the worst thing I've ever had to do. Not Brabourne's truth, and certainly not Emmett's truth in all its searing detail, but a truth of betrayal. A truth she would have found out anyway. The scene that followed was every bit as distressing as you could imagine. But she was no Marjorie, stoic and withdrawn. Gwen just wept in my arms. She got out all the photographs from when Harry was a little boy. There were not a great many but she had kept them carefully, and there were his letters home.'

He gestured to the bureau in the corner.

'Catherine was away. We sat until it became dark. Eventually she lit the lamps, set the fire. I talked about Hugh and Miles for the first time really since their death. Her tears were for them as well as for their unacknowledged half-brother, Harry. Our sons. Some time after midnight we went up to bed.'

Instinctively Laurence looked down at the weapon, which Somers was holding without wavering, then made himself return to the other man's deeply furrowed but still handsome face. The clock on the mantelpiece whirred but did not chime.

'Perhaps it would be for the best...?' Somers began slowly.